A paper by Haberland et al. titled: “Elllpsometer and Reflectance-Anisotropy Measurements on Rotating Samples”, Thin Solid Films, 313-314, (1998) 620-624, describes a method for significantly reducing signal wobble when ellipsometry is performed on rotating samples, the surfaces of which are not oriented normal to the axis of rotation. This paper discloses that placing a spherical mirror in a Spectroscopic Ellipsometer so that it intercepts a beam of electromagnetic radiation that has reflected from a rotating sample surface, and directs it back onto said rotating sample surface so that it again reflects therefrom before entering a detector, serves to reduce distortions in ellipsometric signal spectra caused by said sample wobble.
Also disclosed, because they disclose beam directing means that operate based on Total Internal Reflection or on Specular reflection, are U.S. Pat. Nos. 6,034,777, 6,549,282 and 6,804,004 to Johs et al. which describe methodology for correcting polarizations state effects introduced by beam directing means that rely on specular reflection so that uncorrelated PSI and DELTA of a Sample being investigated can be achieved. Further, U.S. Pat. No. 5,969,818 to Johs et al. describes a four bounce mirror system which performs orthogonal component compensation, and U.S. Pat. No. 5,953,327 to He et al. and Published Application US 2004/0070760 by Stehle et al. describe an ellipsometer or the like in which beam directing means allow a source and detector to be positioned side by side rather than distally from one another along the locus of a sample investigating beam. Further, U.S. Pat. No. 5,929,995 to Johs describes use of beam directing prisms in a vacuum chamber, thereby allowing an electromagnetic beam to reach otherwise an otherwise inaccessible sample therein, no known reference teaches application of the dual reflective surface system which is subject in this disclosure to enable investigation of a rotating sample surface, which surface demonstrates precession in, for instance, an in-situ sample processing apparatus.
No known reference however, discloses, in the context of an ellipsometer or polarimeter system, a dual reflection surface (eg. a prism system, configured to provide a polarized output beam, the locus of which is rotated in direction by 90 degrees, (eg. in a “X”-“Z” plane effected by re-directing an input beam which enters thereinto along a “Y” axis, in an “X”-“Y”-“Z” coordinate system), wherein the second reflection substantially compensates effects of the first, as regards beam Polarization State. This is especially true where a polarized beam of electromagnetic radiation is used to investigate a rotating sample that is “wobbling”, (ie the rotating sample surface is not oriented normal to the sample rotation axis, so that a precession effect occurs during rotation), and wherein practice of a method of use of the system effectively reduces the effect of angular sample wobble on reflected ellipsometer beam signal spectra.
The references identified above are all incorporated by reference into this Disclosure.